Freestyle Line Set not Showing in Blender 2.79
Got it solved, thanks to this video by Blender Nerd ( Thanks ).

https://www.youtube.com/watch?v=6ItWP3lGBGY

Basically you need to first enable / activate "Freestyle" in the Properties > Render Tab. 

Then you can go to the Properties > Render Layers Tab and you'll see a new section called: Freestyle